My wife and I file separate for 1 reason:
She has student loans and the payment is based off of her income. So by doubling her income ( mine and hers ) her payment will be close to 400/month.
By herself - $ 9.97. I know it is crazy.

She is a teacher, so in a total of 10 years ( 7 more left ) - her remaining balances will be forgiven. Not bad.

In the meantime, I cannot write off any deductions - rental loss, tuition, books, ANYTHING>> it sucks.